A variety of devices on the market today utilize electrode coatings comprised of metal oxides or metal nitrides. Depending on how they are deposited, coatings comprised of metal oxides or metal nitrides can have a variety of topographies and morphologies. Traditional metal oxide electrodes, however, are mechanically hard and are sensitive to the build-up of brittle oxide layers at the surface of the electrode. These properties make metal oxide electrodes undesirable for use in applications where flexibility and/or biological compatibility are required.
Conductive polymer coatings have the potential to overcome some of the drawbacks associated with traditional metal oxide or metal nitride coatings. For example, conductive polymer coatings derived from poly(3,4-ethylenedioxythiophene) (PEDOT) have been widely used in the electronics industry. The conductive polymer coatings known in the art, however, have primarily been formulated for application as thin films over flat, two-dimensional substrate surfaces.
It is desirable to develop a conductive coating that provides excellent electrical conductivity, and is biologically acceptable for use in medical device applications, and exhibits greater mechanical, chemical, and electrical stability than the coatings known in the art, such that it is suitable for conformal application to three-dimensional substrate surfaces.
In addition, the conductive polymer coatings known in the art have primarily been applied to rigid, inflexible surfaces. The coatings known in the art often lack flexibility and/or crack resistance, and will often exhibit a loss of conductivity after being subjected to repeated flexing cycles. It is therefore desirable to develop a conductive coating that is mechanically and electrically durable for application to substrate surfaces having a high degree of flexibility.